Fix a precision bug of valueToString, prevent to give an error result… (#1246)

* Fix a precision bug of valueToString, prevent to give an error result on input of wanted precision 0 and a double value which end of zero before decimal point ,such as 1230.01,12300.1;
Add test cases for double valueToString with precision 0;

* Delete a test case with platform differences in the previous commit

* Fix clang-format.

* Fix clang-format!

Co-authored-by: lilei <dlilei@126.com>

.gitignore

@@ -10,6 +10,7 @@
 /libs/
 /doc/doxyfile
 /dist/
+/.cache/
 
 # MSVC project files:
 *.sln
@@ -30,6 +31,7 @@
 CMakeFiles/
 /pkg-config/jsoncpp.pc
 jsoncpp_lib_static.dir/
+compile_commands.json
 
 # In case someone runs cmake in the root-dir:
 /CMakeCache.txt

src/lib_json/json_tool.h

@@ -116,14 +116,18 @@ template <typename Iter> void fixNumericLocaleInput(Iter begin, Iter end) {
  * Return iterator that would be the new end of the range [begin,end), if we
  * were to delete zeros in the end of string, but not the last zero before '.'.
  */
-template <typename Iter> Iter fixZerosInTheEnd(Iter begin, Iter end) {
+template <typename Iter>
+Iter fixZerosInTheEnd(Iter begin, Iter end, unsigned int precision) {
   for (; begin != end; --end) {
     if (*(end - 1) != '0') {
       return end;
     }
     // Don't delete the last zero before the decimal point.
-    if (begin != (end - 1) && *(end - 2) == '.') {
-      return end;
+    if (begin != (end - 1) && begin != (end - 2) && *(end - 2) == '.') {
+      if (precision) {
+        return end;
+      }
+      return end - 2;
     }
   }
   return end;

src/lib_json/json_writer.cpp

@@ -154,16 +154,18 @@ String valueToString(double value, bool useSpecialFloats,
 
   buffer.erase(fixNumericLocale(buffer.begin(), buffer.end()), buffer.end());
 
-  // strip the zero padding from the right
-  if (precisionType == PrecisionType::decimalPlaces) {
-    buffer.erase(fixZerosInTheEnd(buffer.begin(), buffer.end()), buffer.end());
-  }
-
   // try to ensure we preserve the fact that this was given to us as a double on
   // input
   if (buffer.find('.') == buffer.npos && buffer.find('e') == buffer.npos) {
     buffer += ".0";
   }
+
+  // strip the zero padding from the right
+  if (precisionType == PrecisionType::decimalPlaces) {
+    buffer.erase(fixZerosInTheEnd(buffer.begin(), buffer.end(), precision),
+                 buffer.end());
+  }
+
   return buffer;
 }
 } // namespace

src/test_lib_json/main.cpp

@@ -2005,6 +2005,34 @@ JSONTEST_FIXTURE_LOCAL(ValueTest, precision) {
   result = Json::writeString(b, v);
   JSONTEST_ASSERT_STRING_EQUAL(expected, result);
 
+  b.settings_["precision"] = 0;
+  b.settings_["precisionType"] = "decimal";
+  v = 123.56345694873740545068;
+  expected = "124";
+  result = Json::writeString(b, v);
+  JSONTEST_ASSERT_STRING_EQUAL(expected, result);
+
+  b.settings_["precision"] = 1;
+  b.settings_["precisionType"] = "decimal";
+  v = 1230.001;
+  expected = "1230.0";
+  result = Json::writeString(b, v);
+  JSONTEST_ASSERT_STRING_EQUAL(expected, result);
+
+  b.settings_["precision"] = 0;
+  b.settings_["precisionType"] = "decimal";
+  v = 1230.001;
+  expected = "1230";
+  result = Json::writeString(b, v);
+  JSONTEST_ASSERT_STRING_EQUAL(expected, result);
+
+  b.settings_["precision"] = 0;
+  b.settings_["precisionType"] = "decimal";
+  v = 1231.5;
+  expected = "1232";
+  result = Json::writeString(b, v);
+  JSONTEST_ASSERT_STRING_EQUAL(expected, result);
+
   b.settings_["precision"] = 10;
   b.settings_["precisionType"] = "decimal";
   v = 0.23300000;